Apparatus for polishing glass sheets



1960 P; J. KIRKMAN ETAI. 2,923,108

A APPARATUS FOR POLISHING GLASS SHEETS Filed Sept. 6, 1956 2 Shets-Sheei. '1

IN V EN TORS A TTORNE YS Feb. 2, 1960 P. J. KIRKMAN ETAL 2,923,108

APPARATUS FOR POLISHING GLASS SHEETS Filed Sept. 6, 1956 2 Sheets-Sheet 2 INVENTORS p062: and

Y a! 2? 22m NfYS Unite States APPARATUS FOR POLISHING GLASS SHEETS Peter J. Kirkman, Ottawa, and Marshall S. Tisler, Marseilles. Ill., assignors to Libbey-Owens-Ford Glass Compauy, Toledo, Ohio, a corporation of Ohio Application September 6, 1956, SerialNo. 608,393 Claims. (Cl. 51-2 63) The present invention'relates generally to the surfacing of glass, and more particularly to an improved apparatus for polishing glass sheets or plates.

Glass sheets or plates, after having been ground and polished, occasionally incur small scratches on the polished surfaces thereof, which scratches make the sheets objectionable for their ultimate use as windows, windshields or the like. These scratches occasionally are formed in the sheets after they have been cut to final shape and are ready, for example, to be laminated with a plastic interlayer and then used as automobile windows. Consequently, the rejection or scrapping of such a sheet of glass involves not only the loss of the glass, but also the cost of grinding, polishing, handling and cutting of the sheet to final shape. In the past, the removal of such scratches has been accomplished by applying pumice or other suitable mild barasive, in paste form, to the scratched portion of the sheet, and then hand or machine polishing the sheet to remove the scratches. This method of scratch polishing did not prove entirely satisfactory since, among other reasons, the abrasive material could not properly cover the scratched portion of the sheet during the polishing thereof but instead would be thrown outwardly or away therefrom by the rotative action ofv the tool and thus wasted.

Therefore, an important object of the invention is to provide an improved apparatus for polishing glass sheets or plates.

Another object of the invention is to provide an improved apparatus for polishing glass sheets or plates wherein an adequate supply of abrasive material is constantly contacting the portion of the glass sheet to be polished.

A further object of the invention is to provide glass polishing apparatus wherein the polishing abrasive is retained in contact with the polishing tool.

Other objects and advantages of the invention will become more apparent during the course of the following description when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

Fig. 1 is a perspective view of glass polishing apparatus constructed in accordance with the invention;

Fig. 2 is a plan view of another type of glass polishing apparatus constructed in accordance with the invention and shown in operative association with a work table on which glass sheets to be polished are supported;

Fig. 3 is a partial vertical section taken along the line 3-3 of Fig. 2;

Fig. 4 is an end view of the polishing apparatus shown in Figs. 2 and 3;

Fig. 5 is an enlarged fragmentary section taken along the line 5-5 of Fig. 4; and

Fig. 6 is a transverse vertical section taken along the line 66 of Fig. 2.

Briefly stated, the present invention concerns the scratch polishing of glass sheets wherein an abrasive,

7 Patented Feb. 2, 1960 ice 2 with a fluid carrier, is applied evenly to the moistened polishing surface of the improved polishing apparatus constructed in accordance with the invention.

With reference now to the drawings, and particularly to Fig. l, a disk-like polishing wheel 10 is supported for continuous rotation by an axle 11, the opposite ends of which may be rotatably supported in bearings (not shown). Any suitable means of rotation may be used, for example, a pulley 12 may be secured to the shaft and rotated by means of a belt 13 driven by a motor (not shown). The edge of peripheral surface of the wheel is covered by a polishing pad 14 which may be composed of felt or other suitable material which is capable of absorbing liquids. A nozzle 15 is positioned so as to constantly direct a'fine spray of liquid 16, such as water, toward and against the pad 14, said spray being of sufficient width to cover the pad surface a. The nozzle 15 may be supported and supplied with liquid by any suitable means and in the drawings the nozzle is shown threaded into a pipe T 17, the one end of which is closed by a pipe plug 18, and the opposite end of which receives a pipe 19 connected to a source of fluid. Positioned above the nozzle 15, in substantially the same vertical plane therewith, is a second nozzle 20 adapted to emit a fine fluid spray 21 of sufiicient width to entirely cover the surface of the pad 14. The nozzle 20 is threaded into a nipple 22 having a pipe cap 23 closing its one end, and having its opposite end received within the discharge end of a pipe T 24 which, in effect, acts as an aspirator. The opposite or charge end of the T 24 is supplied with a pressurized fluid, such as air, by a pipe line 25 which extends downwardly toward a platform 26 upon which a workman may stand while holding a glass sheet 27 in position for engagement with the polishing disk 10.

To control the fluid passing through the line 25, a valve 28 is provided which valve may be controlled for for opening and closing movement by a pivoted foot pedal 29 supported by the platform 26 and which may be actuated by a workmans foot. The center, or suction tap of the T 24 is connected to an abrasive feed line 30 which, in turn, is joined to a supply tank 31 which contains a suitable abrasive, such as dry pumice.

According to the present invention, the polishing disk 10, while rotating, has the surface a of the polishing pad 14 constantly supplied with a fine spray of water which is emitted from the nozzle 15. This water spray keeps the pad 14 moist so that, as later described, the abrasive may be retained on the surface thereof.

When it is desired to polish a glass sheet, such as the sheet 27 having a scratch 32 on the undersurface thereof, the sheet is presented for tangential contact with the surface a of the polishing pad 14 with the scratch 32 preferably centered on said pad. Prior to engagement of the sheet with the pad surface, the foot lever 29 is actuated to allow air to pass through the valve 28 and out the nozzle 20. While passing through the T 24, the air entrains the abrasive carried by the pipe 30 and draws the abrasive into the T 24 so that the fine spray 21 emitted from the nozzle 20 carries the abrasive against the surface of the polishing pad and substantially evenly coats the surface thereof. Preferably, the valve 29 is held in the open position until the wheel 10 completes at least one revolution so that the entire peripheral surface of the polishing pad is coated with a fine layer of abrasive. The scratch 32 of the glass sheet is then caused to bear against the surface of the polishing pad so as to be acted upon 3 frictional heat which also tends to dry the pad. This tendency of the pad to dry 'is prevented, however, by the action of the 'nozzle which, as previously mentioned, constantly emits a fine spray 16 of watertoward and against the surface of the pad. Thus, the pad is always sufiiciently moist to properly retain the abrasive in contact therewith, and the velocity of the spray is maintained Y numeral 35.

The machine 35 comprises a support frame 36, a machine base 37 rotatably supported upon said frame, and

a movable carriage 38 carried by the machine base which supports a polishing wheel 39 and the associated mechanism for operating the same. The frame 36 includes an upright framework 40 which may be anchored to the floor 41, and a flanged housing 42 extending upwardly from the frame and supporting a rotatable collar 43 which forms a portion of the machine base 37. To support-the collar'43 for rotation about the housing 42, a shaft '44 extends downwardly from said collar through the housing and has its lower end received in a bearing 45 carried by the frame'40.

In addition to the collar 43, the base 37 includes a plate '46, secured to the upper surface of the collar-43, which, as seen in Fig. 6, supports a pair of spaced chan- 'nels 47 disposed in "back to-back relationship with one another. .Each of the-channels 47 has an angle iron stop 48'secured to each end ofthe upper flange thereof which, as later described, serve to limitthe movement'of the carriage 38.

The movable carriage 38 for supporting the polishing wheel 39 and associated mechanism includes a pair of spaced channels 49 arranged in toe-to-toe relationship with one another. Intermediate the ends of the channels 49, approximately at the midpoint thereof, there is provided an axle 50 which extends through the webs of each of the channels and carries at each of its outer ends a Wheel 51 which rides upon the upper flanges of the channels '47. The axle 50 is restrained from transverse movement with respect to the-channels 4-9 by means of flanged bearing blocks 52 through which the axle passes and which are secured to the inner faces of the channel webs.

To prevent lateral displacement of the carriage unit while moving along the support channels 49, a plurality of wheels 53 are secured to the lower flange of each of the channels 49 and engage the webs of the channels 47. With such an arrangement, the carriage 38 may be moved longitudinally the entire length of the channels 47, the wheels 51 being confined in movement along the upper flange of said channels by 'means of the angle stops 43.

The polishing wheel 39 is supported for rotational movement between the ends of the channels 49 by means of an axle 54supported by suitable flanged bearings 55 secured to the channel webs. As shown in Fig. 2, the axle 54 extends outwardly beyond the web of one of the channels and has a sheave 56 carried thereon. To-drive the sheave 56 and thus the wheel 39, an'electric motor 57 is located on the carriage 33 at the-end thereof opposite to that at which the wheel 39 is secured. As shown in'Figs. 2 and 3, the motor 57 is secured to the upper flanges of the channels 49 and has its output shaft 58 extending outwardly on the same side of the carriage 38 as the outwardly extending portion of the axle 54. A sheave 59 is secured to theend of the shaft 58and drives the sheave 56 by means of a 'continuo'ushelt 60. The position of the motor and the weight thereof with respect to the axle 50 is such that the motor overweights the carriage when pivoted about the support wheels 51 and, therefore, there is always a tendency for the carriage end carrying the polishing wheel to rise vertically. To restrain the maximum vertical movement of the carriage to the position shown in Fig. 3, an angle iron 61 is secured to the ends of the channels 47, adjacent the motor 57, and has its upper leg disposed in a horizontal plane.

In pivoting about the axle 50, the bottom flanges of the channels 49,forming a portion of the carriage 38, contact the upper leg of the angle 61 and, therefore, prevent further downward movement of the end of the carriage supporting the motor.

Similarly to the polishing wheel 10, shown in Fig. 1, the wheel 39 is provided with a polishing pad 62 composed of felt or other suitable resilient material which will absorb liquids. The pad is supplied with a "continuous, fi'ne spray of water emitted by a nozzle 63 supported in close proximity to said pad. As best shown in Figs. 3 and 4, the nozzle 63 is in the form of a T and supplied with water by pipes 64 which extend'outwar'dly and upwardly therefrom and are then directed rearwardly along the 'upper flanges of the channels 49 to be joined to flexible pipe sections 65 connected to a'source of water. To retain the water supply pipes 64'in position, the portions thereof extending along the upper flanges of the channels 49 are secured thereto by suitable clamps 66.

To provide handles for selectively locating the polishing Wheel about a glass sheet to be polished, a pair of outwardly extending pipe sections67 are provided which sections, at their inner ends, curve rearwardly and join to the pipe sections 65 leading to the'watersupply.

'As'a means'of'supplying the pad'surface witha fine "spray of abrasive and air, a nozzle 68 is provided and positioned immediately beneath the Water spray nozzle 63 and adjacent the polishing pad 62. The nozzle 63 as supported at one end of the straight run of pipe T 69 having its other end connected through suitable pipe sections 70 and couplings to a hand-actuated air valve 71 connected to a suitable source of air (not shown). The side outlet of the pipe T 69 is supplied with a-dry abrasive compound, such as pumice, by meansof a flexible tube 72 connected to a supply container 73 of abrasive joined by means of a strap 74 to an angle iron 75 extending upwardly from one of the channels 49. As will be later described, the passage of air through the straightrun of the T and into the nozzle 68 has an aspirating or suction effect on the abrasive supplied intermediate the end of said T which entrains said abrasive in the flowing air and projects it through the nozzle and against the surface of the polishing pad 62.

In scratch polishing a glass sheet, such as the sheet 34, according to this invention and with the improved apparatus herein disclosed, a machine operator grasps the handles of the carriage 38 and pulls the carriage-outwardly until the polishing wheel 39 is disposed above the surface of the glass sheet 34 to be polished. A slight amount of downward force applied to the handles will then cause the carriage to rotate about the axle 50 and the polishing pad 62 to engage the surface of the sheet. Prior to engagement of the pad with the glass sheet, the operator presses the hand valve 71 which causes the airsuspended abrasive mixture to be projected against the polishing pad 62. The wheel 39 is then caused to engage the sheet 34 and polish the scratched portion thereof. If additional abrasive material is required during the polishing, it is only necessary for the operator to again actuate the hand valve 71.

Since the surface of the polishing pad 62 is constantly dampened by means of the fine water spray emitted from the nozzle 63, there is no tendency for the abrasive'to cake onthe surface wheel due to the heat of friction. After polishing the sheet 34, the machine carriageand base may then be rotated counterclockwise to engage 5 other sheets 76, shown in phantom lines, on the work table 33 which have previously been positioned by other workmen. Due to the shape of the work table 33 and the construction of the polishing machine 35, the machine may be constantly rotated back-and-forth above the table to scratch polish sheets located thereon.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred embodiment of the same, and various changes may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

We claim:

1. An apparatus adapted to polish glass sheets or plates, including a rotating disc, a liquid absorbent material covering the peripheral surface of the disc, first spray means adapted to direct a fine spray of liquid against and over the liquid absorbent material, pressure control means adapted to control the spray emitted by said first spray means, second spray means adapted to coat the liquid absorbent material with a dry abrasive, said second spray means being operable after said first spray means and before the disc engages a glass sheet, pressure control means adapted to control the spray emitted by said second spray means, and means for supporting the apparatus in position to engage a glass sheet.

2. An apparatus as defined in claim 1, wherein the support means for the apparatus includes an upright framework, a support plate, means for mounting said support plate to said framework for 360 angular rotation, a first pair of spaced channels affixed to said plate and having outwardly flaring upper and lower flanges disposed in back to back relationship with one another, a movable carriage, means for mounting said movable carriage for movement longitudinally with respect to said first channels, and means for mounting the rotating disc on said movable carriage.

3. An apparatus as defined in claim 2, wherein said movable carriage includes a second pair of spaced channels having outwardly flaring upper and lower flanges arranged in toe to toe relationship with each other, an axle intermediate the ends of said second channels, means for limiting the transverse movement of said axle with respect to said second channels, a pair of wheels mounted on said axle adapted to ride upon the upper flange of the first mentioned channels whereby the carriage is freely movable in a direction longitudinal of said first mentioned channels, and means mounted on the upper flanges or" said first channels limiting the longitudinal movement of the movable carriage.

4. Apparatus for polishing glass sheets or plates as defined in claim 1 wherein said second spray means includes fluid conveying means for delivering a fluid carried abrasive under pressure to said second nozzle said fluid conveying means including an aspirator having a charging opening, a suction opening, and a delivery opening, a source of abrasive connected to said suction opening, and a pressure line for conveying fluid under pressure to said charging'opening.

5. Apparatus for polishing glass sheets or plates as defined in claim 4, wherein said pressure control means for said second spray means are positioned in said pressure line for controlling the flow of fluid therethrough.

References Cited in the file of this patent UNITED STATES PATENTS 1,618,085 Hess Feb. 15, 1927 1,725,899 Chase Aug. 27, 1929 1,801,314 Landolt Apr. 21, 1931 2,332,992 Davis Oct. 26, 1943 2,409,340 Bohler Oct. 15, 1946 2,471,727 Creamer May 31, 1949 2,677,219 Burt May 4, 1954 

